Various long-chain fatty acid glycerides containing short-chain hydroxy acid substituents have been disclosed in the art for use primarily as food emulsifiers. For example, U.S. Pat. No. 2,690,971, Iveson, et al., issued Oct. 5, 1954, relates to shortening addition agents formed by reacting glycerine, higher fatty acids containing from 12 to 20 carbon atoms, and alpha-hydroxy acids containing less than 6 carbon atoms. Mixed diglycerides containing both the long-chain acid and short-chain hydroxy acid groups are the desired product, but up to 25% monoglycerides, including short-chain alpha-hydroxy monoglycerides, are formed in the reaction. Similar short-chain alpha-hydroxy monoglycerides are disclosed in U.S. Pat. No. 2,957,932, Radlove, et al., issued Oct. 25, 1960 and in U.S. Pat. No. 2,966,410 Chang, et al., issued Dec. 27, 1960.
Long-chain alpha-hydroxy monoglyceride compounds have also been disclosed in the art. For example, Japanese Pat. No. 49-55752, Uoi, et al., published May 30, 1974, discloses polycarbonate-resin molding compositions containing minor amounts of higher alpha-hydroxy fatty acid monoglycerides as mold-release and fluidizing agents. The patent states that its alpha-hydroxy acids should have long hydrocarbon chains and exhibit relatively high melting points. Only alpha-hydroxy palmitic, stearic and arachidonic acid monoglycerides are disclosed. Also, U.S. Pat. No. 2,108,725, Rieche, et al., issued Feb. 15, 1938, describes compounds of the formula RCH(X)COR.sup.1 where X is a hydrophilic radical which can be hydroxy, amino or ammonio and R.sup.1 is hydroxy, an alcohol radical or a substituted or unsubstituted amine. The compounds are derived from alpha-halo fatty acids and are said to be useful as emulsifying, cleaning or softening agents. Example VI describes the preparation of alpha-hydroxy stearic acid from alpha-bromo stearic acid. In the form of its monoglyceride, the product is said to be a highly active emulsifying agent for the preparation of pastes, ointments, and creams, especially for cosmetics.
Various sugar esters of hydroxy fatty acids are described in the art. For example, Simonis, et al., Detergent Activity of Hydroxylated Esters of Saccharose and Fatty Acids, Agnew. Chem., 75(16/17): 791 (1963), discloses that esters of sugars and fatty acids containing 1 or more hydroxy groups possess high detergent activity. Examples include saccharose 12-hydroxystearate and saccharose 9,10-dihydroxystearate. Also, Tulloch, et al., Extracellular Glycolipids of Rhodotorula Species, Canadian Journal of Chemistry, 42:830-835 (1964), discloses the biosynthesis of extracellular glycolipids from several species of red yeast. The glycolipids consist of a mixture of the mannitol and pentitol esters of beta-hydroxy palmitic and stearic acids.
Finally, U.S. Pat. No. 2,652,410, Cunningham, et al., issued Sept. 15, 1953, discloses the reaction of alpha-hydroxy acids and/or their estolides with polyhydric alcohols to form partly or completely gelled esterification mixtures. The gelled mixtures are said to be useful as linoleum cementing compositions, and when highly dehydroxylated, as substitutes for linseed oil and drying oils. The patent states that four possible reactions may occur singly, simultaneously or consecutively, depending on the reaction conditions. They are estolide formation, esterification of the acids and estolides, dehydroxylation of the acids, estolides and esters, and polymerization.